Effects of Feed Processing and Frequency of Feeding on Ruminal Fermentation, Milk Production, and Milk Composition1 T. H. KLUSMEYER, M. R. CAMERON, G. C. McCOY, AND J. H. CLARK2 Department of Animal ScIences University of Illinois 1207 West Gregory Drive
Urbana 61801
lowered nnninal fluid pH and a decreased ratio of acetate to propionate in cows consuming the cubed diet. Even though nnninal fluid pH and the ratio of acetate to propionate tended to be lower when cows were fed four times rather than two times per day, production and composition of milk were not affected by frequency of feeding the diets. (Key words: physical fonn, frequency of feeding, nnninal fermentation)
ABSTRACT
Twenty Holstein cows, averaging 108 d postpartum, were used in five replicated 4 x 4 Latin squares to investigate the effects of feed processing and frequency of feeding on nnninal fennentation, milk production, and milk composition. Four rumen~fistu1ated cows were used in one of the replicates to monitor nnninal fermentation. Each cow was fed for ad libitum intake a diet of 55% alfalfa and 45% concentrate on a DM basis. Treatments were 1) noncubed diet fed two times daily, 2) noncubed diet fed four times daily, 3) cubed diet fed two times daily, and 4) cubed diet fed four times daily. Alfalfa was fed as long hay in the noncubed diet and chopped and pressed into a cube in the cubed diet. Dry matter intake by cows was not different between treatment comparisons. However, cows fed the noncubed diet consumed 5% more concentrate and 5% less alfalfa than did cows fed the cubed diet. Milk production was greater (1.4 kg/d) when the cubed diet was fed to cows, but the percentage and yield of milk fat were depressed (.43 percentage units and .09 kg/d), causing a decreased production of 4% FCM (.9 kg! d). The depression in milk fat percentage and yield may have been attributed to
INTRODUCTION
Received December 27. 1989. Accepted March 30, 1990. ISupported in part by the University of Dlinois Agricultum! Experiment Station; Illinois State Department of Agriculture; lllinois Com Mar:lcetiJJg Board; Emerald Acres, Inc., New Richmond, IN; Pekin Energy Company, Pekin, IT..; and a gift from the Commodity Credit Corporation. USDA. 2Address correspondence to: Jimmy H. Clark, Department of Animal Sciences, University of Illinois, 315 Animal Science Laboratory, 1207 W. Gregory Drive, Urbana, IT.. 61801. 1990 J Dairy Sci 73:3538-3543
Feeding cubes of alfalfa and concentrate that supply a total mixed ration to dairy cows may be beneficial, because the cubes provide all required nutrients, decrease transportation cost for feeds, and reduce feed wastage from the feed bunk. However, alfalfa hay must be chopped before it can .be p£?Cessed ~to a ~be and reducing the particle sIZe of high quality alfalfa has decreased the fat content of milk because of an altered ruminal fermentation in some (17, 20) but not all trials (19). The alteration in ruminal fennentation for cows fed alfalfa pellets may result from less time chewing, which may decrease saliva flow to the rume~ and the buffering of end products of the rununal fermentation (17, 20). Ruminal fermentation has been improved by increasing the frequency of feeding diets to ruminants (9, 11, 12). Gibson (7) suggested that frequent feeding of high concentrate diets improved milk fat percentage. Therefore, the objective of this ~ was to investigate the effects of feed processmg and frequency of feeding on ruminal fennentation, milk production, and milk composition. MATERIALS AND METHODS Experimental Design, Management of Cows, and Diets
Twenty Holstein cows were used in five replicated 4 x 4 Latin squares with 28-d per-
3538
PHYSICAL FORM AND FREQUENCY OF FEEDING
iods. The first 14 d were used for adjustment to treatments followed by 14 d of data collection. At the beginning of the experiment. cows ranged from 53 to 157 d postpartum and averaged 108 d The four treatments were 1) noncubed diet fed two times daily, 2) noncubed diet fed four times daily, 3) cubed diet fed two times daily, and 4) cubed diet fed four times daily. Cubes were formed by passing dietary ingredients through a 3.2-cm2 die in a cubing machine (Emerald Acres, Inc., New Richmond, IN). Ingredient composition of the cubes was chopped alfalfa. 55%; com gluten feed, 21.9%; ground shelled com, 20.0%; dry molasses, 2.5%; NaCl, .5%; and trace mineral and vitamin mix, .1 %. Dietary ingredients in the noncubed and cubed diets were offered to cows in the same ratio from feeds obtained from the same sources. Alfalfa was fed as long hay in the noncubed diet. Alfalfa was chopped and other feed ingredients were ground prior to cubing. Cows fed noncubed and cubed diets two times daily were offered feed at 1100 and 2300 h. Cows fed the cubed diet four times daily were offered feed at 0500, 1100, 1700, and 2300 h. Cows fed the noncubed diet four times daily were off~ grain at 0500, 1100, 1700, and 2300 h and long alfalfa hay at 1100 and 1700 h to provide about a 5% refusal. Cubed diets and noncubed diets were fed to cows so that they did not refuse more than about 5% of the feed that was offered, and for cows fed noncubed diets only hay was refused. Feed samples were wet sized according to the procedures of Woodford and Murphy (20). Particle size averaged 1117, 1007, and 1601 J.l1D; and SD (108ro) were .32, .32, and .38 for concentrate, cubed diet. and a mixture of dietaIy ingredients sampled prior to cubing, respectively. The cubing process decreased the particle size of the cubed diet to values that were less than the particle size of the mixture of dietary ingredients because of pressure a~ plied to the feeds, which further decreased particle size. Dry Matter Intake, Milk
and Milk Composition
Production,
Dry matter intake was measured daily. Samples of alfalfa, concentrate, and cubed diet were
3539
sampled weekly and composited. Dry matter content of feed samples was detennined by drying in a forced-air oven at SS"C for 48 h. Dried samples were ground in a Wiley mill (Arthur A. Thomas, Philadelphia, PA; 2-mm screen) and analyzed for organic matter, CP (1), ADF, and NDF (8). Milk. production was measured daily at 0630 and 1630 h, and production from the last 14 d of each period was used to calculate treatment means. On d 20 and 21 and d 27 and 28 of each period, milk samples were taken from four consecutive milkings and preserved with 2bromo-2-nitropropane-l,3 diol. Daily a.m. and p.m. samples were composited according to milk production and analyzed for SNF (10), protein. and fat content (infrared analysis, Dairy Lab Services, Inc., Dubuque, IA). Rumlnal
Fermentation
Four cows assigned to one replicate of the 4
x 4 Latin squares were surgically fitted with ruminal fistul.aes. On d 27 of each period, rumen-fistulated cows were dosed at 1900 h with 50 g sodium cobalt-EDTA dissolved in 500 ml of water as described by Uden et al. (18) to determine ruminal fluid dilution rate. Samples of ruminal fluid were taken hourly for 24 h beginning at 1800 h from the mmen via a suction pump. Ruminal fluid pH was determined (glass electrode), and samples were acidified to pH 2 with 50% H2S04. Samples were centrifuged at 27,fXXJ X g for 10 min, and the supernatant was frozen until analyzed for cobalt. VFA, and ammonia. Cobalt content of the ruminal fluid was measured with an atomic absorption spectrophotometer (perkin-Elmer 2380, Norwalk, CI') equipped with an air-acetylene flame. The concentration of VFA was determined according to the procedures of Erwin et at. (6) with an automated gas chromatograph (Varian Model 4600, Palo Alto, CA). Concentrations of ammonia in ruminal fluid were determined according to the procedure of Chaney and MaIbach (2) as modified by Cotta and Russell (3). On d 24 of each period, ytterbium chloride (YbCl3·6H20) was dissolved in distilled water (3 g Yb/150 ml water) and sprayed onto 1.8 kg of foed ingredients mixed in the same proportions as was offered to the cows. the Yb-labeled Journal of Dairy Scimce VoL 73.
No. 12, 1990
3540
KLUSMEYER ET AL.
TABLE 1. Nutrient composition of feedstuffs.
Component
Alfalfa
Concentrate l
DM OM2 cp 2 ADp2 NDp2
83.3 90.5 20.1 32.6 43.5
88.5 94.4 14.9 7.3 26.2
Cubed diet
Statistical Analysis Noncubed diet
(%) 84.1 88.9 17.7 20.5 36.0
85.6 92.3 17.8 21.2 35.7
IContains: com gluten feed, 48.7%; ground sbellcd corn, 44.4%; dry molasses, 5.6%; salt, 1.1%; trace minera1 and vitamin mix, .2; (cobalt, .004%; copper, .5%; iodine, .025%; iron, 2.0%; magnesium, 5.0%; manganese, 3.0%; potassium, 7.5%; selenium, .015%; sulfur, 10.0%; zinc, 3.0%; vitamin A, 2200 1U/g; vitamin DJ, 660 1U/g; vitamin
E, 8 IU/g). 2All values on a DM basis.
diet was not washed and was fed at 1100 h. Ruminal particle samples were taken via ruminal cannulaes at 6, 12, 18, 24, 30, 36, 42, and 48 h postfeeding. Samples of ruminal particles were dried at 55°C until sample weight did not change. Samples were then ground in a Wiley mill (2-mm screen) and analyzed for Yb with an atomic absorption spectrophotometer according to the procedures of Ellis et al. (5) using 3 M HN03 and 3 M HCl solutions.
Data were analyzed by the general linear model procedure of SAS (16). The single degree of freedom orthogonal comparisons were 1) noncubed versus cubed diet, 2) feeding two versus four times per day, and 3) interaction between physical form of diet and frequency of feeding. RESULTS AND DISCUSSION NutrIent Content of Feeds
Nutrient composition of alfalfa, concentrate, cubed diet, and noncubed diet are shown in Table 1. The alfalfa was an excellent quality forage that contained 20.1 % CP, 32.6% ADF, and 43.5% NDF. The cubed and noncubed diets contained approximately 17.75% CP, 20.85% ADF, and 35.85% NDF. Dry Matter Intake, Milk Production, and Milk Composition
.Dly matter intake was not different for cows consuming noncubed and cubed diets (Table 2). However, cows fed the noncubed diet consumed 5% more concentrate and 5% less alfalfa even though they were offered the feed in the same ratio as was in the cubed diet. Other studies with dairy cows consuming high quality
TABLE 2. Least squares means for DM intake (DMI), milk production. and milk composition by cows fed noncubed or cubed diet offered two (2x) or fom (4x) limes daily.l
p
Urbana 61801
lowered nnninal fluid pH and a decreased ratio of acetate to propionate in cows consuming the cubed diet. Even though nnninal fluid pH and the ratio of acetate to propionate tended to be lower when cows were fed four times rather than two times per day, production and composition of milk were not affected by frequency of feeding the diets. (Key words: physical fonn, frequency of feeding, nnninal fermentation)
ABSTRACT
Twenty Holstein cows, averaging 108 d postpartum, were used in five replicated 4 x 4 Latin squares to investigate the effects of feed processing and frequency of feeding on nnninal fennentation, milk production, and milk composition. Four rumen~fistu1ated cows were used in one of the replicates to monitor nnninal fermentation. Each cow was fed for ad libitum intake a diet of 55% alfalfa and 45% concentrate on a DM basis. Treatments were 1) noncubed diet fed two times daily, 2) noncubed diet fed four times daily, 3) cubed diet fed two times daily, and 4) cubed diet fed four times daily. Alfalfa was fed as long hay in the noncubed diet and chopped and pressed into a cube in the cubed diet. Dry matter intake by cows was not different between treatment comparisons. However, cows fed the noncubed diet consumed 5% more concentrate and 5% less alfalfa than did cows fed the cubed diet. Milk production was greater (1.4 kg/d) when the cubed diet was fed to cows, but the percentage and yield of milk fat were depressed (.43 percentage units and .09 kg/d), causing a decreased production of 4% FCM (.9 kg! d). The depression in milk fat percentage and yield may have been attributed to
INTRODUCTION
Received December 27. 1989. Accepted March 30, 1990. ISupported in part by the University of Dlinois Agricultum! Experiment Station; Illinois State Department of Agriculture; lllinois Com Mar:lcetiJJg Board; Emerald Acres, Inc., New Richmond, IN; Pekin Energy Company, Pekin, IT..; and a gift from the Commodity Credit Corporation. USDA. 2Address correspondence to: Jimmy H. Clark, Department of Animal Sciences, University of Illinois, 315 Animal Science Laboratory, 1207 W. Gregory Drive, Urbana, IT.. 61801. 1990 J Dairy Sci 73:3538-3543
Feeding cubes of alfalfa and concentrate that supply a total mixed ration to dairy cows may be beneficial, because the cubes provide all required nutrients, decrease transportation cost for feeds, and reduce feed wastage from the feed bunk. However, alfalfa hay must be chopped before it can .be p£?Cessed ~to a ~be and reducing the particle sIZe of high quality alfalfa has decreased the fat content of milk because of an altered ruminal fermentation in some (17, 20) but not all trials (19). The alteration in ruminal fennentation for cows fed alfalfa pellets may result from less time chewing, which may decrease saliva flow to the rume~ and the buffering of end products of the rununal fermentation (17, 20). Ruminal fermentation has been improved by increasing the frequency of feeding diets to ruminants (9, 11, 12). Gibson (7) suggested that frequent feeding of high concentrate diets improved milk fat percentage. Therefore, the objective of this ~ was to investigate the effects of feed processmg and frequency of feeding on ruminal fennentation, milk production, and milk composition. MATERIALS AND METHODS Experimental Design, Management of Cows, and Diets
Twenty Holstein cows were used in five replicated 4 x 4 Latin squares with 28-d per-
3538
PHYSICAL FORM AND FREQUENCY OF FEEDING
iods. The first 14 d were used for adjustment to treatments followed by 14 d of data collection. At the beginning of the experiment. cows ranged from 53 to 157 d postpartum and averaged 108 d The four treatments were 1) noncubed diet fed two times daily, 2) noncubed diet fed four times daily, 3) cubed diet fed two times daily, and 4) cubed diet fed four times daily. Cubes were formed by passing dietary ingredients through a 3.2-cm2 die in a cubing machine (Emerald Acres, Inc., New Richmond, IN). Ingredient composition of the cubes was chopped alfalfa. 55%; com gluten feed, 21.9%; ground shelled com, 20.0%; dry molasses, 2.5%; NaCl, .5%; and trace mineral and vitamin mix, .1 %. Dietary ingredients in the noncubed and cubed diets were offered to cows in the same ratio from feeds obtained from the same sources. Alfalfa was fed as long hay in the noncubed diet. Alfalfa was chopped and other feed ingredients were ground prior to cubing. Cows fed noncubed and cubed diets two times daily were offered feed at 1100 and 2300 h. Cows fed the cubed diet four times daily were offered feed at 0500, 1100, 1700, and 2300 h. Cows fed the noncubed diet four times daily were off~ grain at 0500, 1100, 1700, and 2300 h and long alfalfa hay at 1100 and 1700 h to provide about a 5% refusal. Cubed diets and noncubed diets were fed to cows so that they did not refuse more than about 5% of the feed that was offered, and for cows fed noncubed diets only hay was refused. Feed samples were wet sized according to the procedures of Woodford and Murphy (20). Particle size averaged 1117, 1007, and 1601 J.l1D; and SD (108ro) were .32, .32, and .38 for concentrate, cubed diet. and a mixture of dietaIy ingredients sampled prior to cubing, respectively. The cubing process decreased the particle size of the cubed diet to values that were less than the particle size of the mixture of dietary ingredients because of pressure a~ plied to the feeds, which further decreased particle size. Dry Matter Intake, Milk
and Milk Composition
Production,
Dry matter intake was measured daily. Samples of alfalfa, concentrate, and cubed diet were
3539
sampled weekly and composited. Dry matter content of feed samples was detennined by drying in a forced-air oven at SS"C for 48 h. Dried samples were ground in a Wiley mill (Arthur A. Thomas, Philadelphia, PA; 2-mm screen) and analyzed for organic matter, CP (1), ADF, and NDF (8). Milk. production was measured daily at 0630 and 1630 h, and production from the last 14 d of each period was used to calculate treatment means. On d 20 and 21 and d 27 and 28 of each period, milk samples were taken from four consecutive milkings and preserved with 2bromo-2-nitropropane-l,3 diol. Daily a.m. and p.m. samples were composited according to milk production and analyzed for SNF (10), protein. and fat content (infrared analysis, Dairy Lab Services, Inc., Dubuque, IA). Rumlnal
Fermentation
Four cows assigned to one replicate of the 4
x 4 Latin squares were surgically fitted with ruminal fistul.aes. On d 27 of each period, rumen-fistulated cows were dosed at 1900 h with 50 g sodium cobalt-EDTA dissolved in 500 ml of water as described by Uden et al. (18) to determine ruminal fluid dilution rate. Samples of ruminal fluid were taken hourly for 24 h beginning at 1800 h from the mmen via a suction pump. Ruminal fluid pH was determined (glass electrode), and samples were acidified to pH 2 with 50% H2S04. Samples were centrifuged at 27,fXXJ X g for 10 min, and the supernatant was frozen until analyzed for cobalt. VFA, and ammonia. Cobalt content of the ruminal fluid was measured with an atomic absorption spectrophotometer (perkin-Elmer 2380, Norwalk, CI') equipped with an air-acetylene flame. The concentration of VFA was determined according to the procedures of Erwin et at. (6) with an automated gas chromatograph (Varian Model 4600, Palo Alto, CA). Concentrations of ammonia in ruminal fluid were determined according to the procedure of Chaney and MaIbach (2) as modified by Cotta and Russell (3). On d 24 of each period, ytterbium chloride (YbCl3·6H20) was dissolved in distilled water (3 g Yb/150 ml water) and sprayed onto 1.8 kg of foed ingredients mixed in the same proportions as was offered to the cows. the Yb-labeled Journal of Dairy Scimce VoL 73.
No. 12, 1990
3540
KLUSMEYER ET AL.
TABLE 1. Nutrient composition of feedstuffs.
Component
Alfalfa
Concentrate l
DM OM2 cp 2 ADp2 NDp2
83.3 90.5 20.1 32.6 43.5
88.5 94.4 14.9 7.3 26.2
Cubed diet
Statistical Analysis Noncubed diet
(%) 84.1 88.9 17.7 20.5 36.0
85.6 92.3 17.8 21.2 35.7
IContains: com gluten feed, 48.7%; ground sbellcd corn, 44.4%; dry molasses, 5.6%; salt, 1.1%; trace minera1 and vitamin mix, .2; (cobalt, .004%; copper, .5%; iodine, .025%; iron, 2.0%; magnesium, 5.0%; manganese, 3.0%; potassium, 7.5%; selenium, .015%; sulfur, 10.0%; zinc, 3.0%; vitamin A, 2200 1U/g; vitamin DJ, 660 1U/g; vitamin
E, 8 IU/g). 2All values on a DM basis.
diet was not washed and was fed at 1100 h. Ruminal particle samples were taken via ruminal cannulaes at 6, 12, 18, 24, 30, 36, 42, and 48 h postfeeding. Samples of ruminal particles were dried at 55°C until sample weight did not change. Samples were then ground in a Wiley mill (2-mm screen) and analyzed for Yb with an atomic absorption spectrophotometer according to the procedures of Ellis et al. (5) using 3 M HN03 and 3 M HCl solutions.
Data were analyzed by the general linear model procedure of SAS (16). The single degree of freedom orthogonal comparisons were 1) noncubed versus cubed diet, 2) feeding two versus four times per day, and 3) interaction between physical form of diet and frequency of feeding. RESULTS AND DISCUSSION NutrIent Content of Feeds
Nutrient composition of alfalfa, concentrate, cubed diet, and noncubed diet are shown in Table 1. The alfalfa was an excellent quality forage that contained 20.1 % CP, 32.6% ADF, and 43.5% NDF. The cubed and noncubed diets contained approximately 17.75% CP, 20.85% ADF, and 35.85% NDF. Dry Matter Intake, Milk Production, and Milk Composition
.Dly matter intake was not different for cows consuming noncubed and cubed diets (Table 2). However, cows fed the noncubed diet consumed 5% more concentrate and 5% less alfalfa even though they were offered the feed in the same ratio as was in the cubed diet. Other studies with dairy cows consuming high quality
TABLE 2. Least squares means for DM intake (DMI), milk production. and milk composition by cows fed noncubed or cubed diet offered two (2x) or fom (4x) limes daily.l
p
